Of recent years, there has been an increasing use of credit cards carrying machine readable coding identifying the cardholder's account and including further relevant information, including, in an encoded form, a Personal Identification Number, or PIN, known to the cardholder but not appearing on the card in human readable form. Entry by a cardholder of his PIN in a machine equipped to read the encoded information of the card may be used to confirm a transaction in place of the usual requirement of signed authorization. Although various systems have been developed for storing the encoded information, the currently preferred system utilizes a magnetically striped card carrying two parallel tracks, the information in at least one track (Track 1) being a standardized (ANSI X9.8) format. This in turn facilitates the use of standardized credit card readers. Standards have also been developed for communicating and encrypting data exchanged between data entry terminals and host computers.
Systems have also been developed which will accept data from more than one class of card.
In British Pat. No. 1,019,702 (Jones), a point of sale terminal has a reader which reads both product data from product labelling, and customer data from credit cards, but both are accepted sequentially as part of a single transaction in a transaction mode.
U.S. Pat. No. 4,300,042 (Odenkamp et al) discloses apparatus for generating different types of card for use in a system. One type of card is a programming card for modifying data in a system, but there is no description of how such cards are actually used.
In the apparatus of U.S. Pat. No. 3,996,450, a reader will accept ordinary credit cards, and also a supervisory card which places the apparatus in a mode in which it can alter data in an ordinary credit card. The effect of the supervisory card is to change the manner in which the apparatus treats a credit card.
Proposals have also been made for portable data entry devices for manual entry of numerical and code data, which can then be conveyed to a fixed terminal for further processing. An example of such a device is disclosed in U.S. Pat. No. 4,125,871 (Martin).